Magnetic axis and polarity testing device



July 7. 1953- H. DUKE: ETAL MAGNETIC AXIS Ann Romans: msrmc DEVICE Filed Nov. 25, 195p f am Zr, Z My;

July 7, 1953 DUKE ETAL nuns-Hours ANDJ'OLARITY ms'rmc nsvrcs Filed-Nov. 35;, 1950 3 Sheets-Sheet 2 IN V EN TOR, wry Jule Bali/e116. Freenlmad 1 Jean 22am 3y I I my Patented July 7, 1953 PATENT OFFICE 'MKGNETICT-AXIS'IANDWOIJARITYTESTING mzvlcn an indication orfluieangular position of me pick-up 0011' within the inductor. Atst dsfci11a-' minimum and" an axis of maximum eleiotroix'i:aigntic field Strength. By. moving th i nidicafiilfi' g' arm an pic -up coil s'eCu'td thel to ffo'rh th produced by the e erzgization or an -canto the poir'it or immum o'r maiiixrium field strefigfr'ipi'b'diiced' by the" ene'rgiztion of a sec na czsn, aflbriflaiisof can observe the angular displace= ment' btiiveenthetwoirigignetic aXe'S n flig sca'jle me ber secured to the base. Aii' adjustable inm ctor; con c'tmg pin-locating means positioned ad'j'akfifii 'th'e' homing means and oopemtiiig" with a scene secured tothe hoidingmeansifi fn iits'iife op'r'atdr to compare the :mguraw ae- 7 bpn'er obj'ct s and 'ldvantages of the in vbiitioii will' be aiqbdrefiv from the description in Fig 2' isi'ci'o'ss sctional' vi'ew takeri' along line 2 2 iii Fig-. 1 showing-mi inductorunitin testing bosititinfifl the axis dtermining'and indicziflifig' 'dpfiafatfis'; I

Fig.- 3' is azi stringed-fragmentary sectional fiaikr'i'ajlbli'g lin'e' 3 4 in Fig "2 disclosing a 'e lec romagiietic pick-lip coil and means for ifffiicailly "adjii'stihg the bositio'n of the pick-up coil reiamvs 'to' fihe' inductor unit --under test;

FIE. is an enlarged fragmentary sectional wfiwia 'ri'aidhg lirie 4 in Fig. 2 showing the;

fiidiiiiihe'ansioi the inductor unit; 7 Fig. 5 is an erilaigedfrag'mentary topsectior ial v'iw 'tfiitn" along" 'line" in Fig, '3 disclosing.

t1i'{iiiiik'=up coil "vertical adjusting means;

ein enlarged fmg-mentary secfiion'a l" Fig. 7 is a fragmentary elevational view taken along line in Fig. 1 of a means for locking the pick-up coil adjusting means in a predetermined vertical position;

Fig. 8 is an enlarged sectional view taken along 4 viewed in Fig. 1. A block 52 is secured to the base plate 23 adjacent the outer edge of plate 31 so that an index mark 53 etched on block 52 is displaced 90 clockwise from index mark 36 on block 34. Therefore, when index mark 28 is moved intoalignment with the normally aligned marks 32, '33 and 36, mark 21 is in alignment with the normally aligned marks 50, 5| and 53.

A plurality of legs 54 (Fig. 2) which are secured tothe base plate 23 support an apertured plate 55 a predetermined distance above the upper surface of plate 23. An apertured gear housing 56 havinga' depending flange 51 is secured to the upper surface of the plate 55 with the apertures of the plate 55 and gear housing 56 in alignment. An internal ring gear 58 (Figs. 2 and 4) is rotatably mounted'on an upper surface of the gear Referring now to the drawings, wherein like plate is secured to a wooden base 2| (Fig. 2)

so that an opening in the plate 20 is aligned with an opening 22 in the wooden base 2|. An adjustable base plate 23, having a handle 24 .secured to the plate 23, is rotatablypositioned on the fixed base plate 20 so that an opening therein is in alignment with the opening 22.

A quadrant plate 25 rests upon an upper surface of the adjustable base plate 23 and is secured to a bushing |8 which extends through the aligned openings in plates 20 and 23 into opening 22. the opening 22 so that the quadrant plate 25 is movable over the upper surface of the adjustable base plate 23. A knurled thumbscrew 26 (Fig. 1) extends through a slot IS in plate 25 to engage a threaded aperture in the adjustable base plate 23 so that the thumbscrew 26 may be tightened to secure plate 25 in a predetermined position on plate 23. The quadrant plate 25 is also provided at its outer edge with a pair of etched index marks 21 and 28 which are angularly displaced from each other by 90 plus or minus 0 1'.

An adjustable scale plate 29 having an arcuateslot 30 therein is secured in a desired position on the base plate 23 adjacent the outer periphery of quadrant plate 25 by a pair of thumbscrews 3| which extend through the .slot 3|] (Fig.

1) toengage threaded apertures in the base plate r 23 (Fig. 2). A scale portion 42 of the'plate 29 (Fig. 1) adjacent the periphery of the quadrant plate 25 is calibrated in degrees of angular deflection from a mid-zero degree index mark 32. A second zero degree index mark 33. is etched on the upper and outer-surface of the plate 29 in alignment with the zero. index mark 32. A block 34 is secured to the base plate 23 by apair of screws 35 adjacent the outer edge of plate 29 so that an index mark 36 etched on block 34 is in alignment with both of the index-marks 32 and 33. The index mark 36 is designated X. 7

Another adjustable scale plate 31 (Fig. 1) having an arcuate slot 38' therein is secured in a predetermined position on the base plate 23 by a pair of thumbscrews 39 which extend through the slot 38 to engage threaded apertures in the base plate 23. A scale portion 43of the plate 31 adjacent the outer edge of the quadrant plate 25 is calibrated the same as plate 29 (Fig. 1) in degrees of angular deflection from a mid-zero degree index mark 50. An index mark 5| is etched on the upper surface'of the plate 31 in alignment with the index mark but positioned on the outer or lowermost edge of plate 31 as The bushing I8 is rotatably mounted in housing 56. A hole 59 is provided in the outer edge of the ring gear 58- so that a tool may be manually inserted therein through a keyway 40 in the gear housing 56 to rotate the ring gear 58 within the housing 56.

Three planetary gears .56 (Fig. 4) are rotatably mounted on three shafts 6| which are secured tojthe gear: housing 56 so that the teeth of the gears semen; with the teeth of the ring gear 58. A clutch pin 62 is secured to each of the gears. 60. A spur gear 63 having a counterbored upper surface is rotatablymounted on a shaft 64 secured to the gear housing 56 (Fig. 8) so that the teeth of the'gear 63 mesh with the teeth of the ring gear 58. One end of afiat spiral spring 65is secured to the. gear 63 and theother end is secured to the shaft 64' so that the convolutions of the spring arepositioned within the counterbored depression in the upper surface of the gear 63. A gear housingcover plate 58 is secured to an upper extremity of the shafts 6| (Fig. 8) by a plurality of screws 6.1. Thecover plate 66 (Figs. 1 and 2) is provided with a round central opening 68 and three arcuateslots 69 through which the upstanding clutch pins 62 extend. A circular scale portion II on the outer periphery of the cover plate 66 is calibrated from 0 to 360 of angular deflection with the zero degree (0) markthereofin alignmentwith the index mark 36 on block.34.

.When ring gear 58 is manually rotated in a counterclockwise direction, the, three gears 69 are alsorotated in a counterclockwise direction to move the projecting gripping pins 62 away from each other and outwardly from the central opening 68. .The counterclockwise rotation of ring gear 58 also rotates gear 63 in a counterclookw-isedirctioh to wind up spiral spring 65.

After an inductor 10. (Fig. 2) to'be tested is placed on the plate 66 with the inner cylindrical cavityofthe-inductor T0 aligned with the opening 68, theoperator releases the ring gear 58 so that the resilient action of the spring 65 rotates: gear 63.-in alclockwise direction to move both ring gear 58 and gears 60 in a clockwise direction until the pins 62 engage the outer surface of the inductor 10 to secure it in adjusted position on-the plate 66. The continuing resilient action of-spring 65, which is not completely unwound, maintains the pins .62 in gripping engagement with the outer surface of inductor 10 and thereby secures it in a central position on plate 66. r Y I I A-right angle bracket (Fig.2) havinga bifurcated upright portion. 8| is rotatably mounted on the flanged portion51 of the gear housing 56 by a lower annularv horizontal portion 82 of the bracket 80.. .A knurled thumbscrew 83 passing swimthrougm-alower extremity .of thenpright portion 8 I engages .thezouter :edge of they gears. housing 5 6 to clamp the bracketaBIl ma 1 predetermined angularposition adjacent .theplate G6. Two upwardly extending armssMcandrBE w (Fig. '6) of :the bracket B0.are.jo-ined together by a cross bar 86 at the upper extremity thereofrto provide avertical channel :81 in I which' anyinductor connecting pin locating armi88 .is adjustably zsecured. The locating arm 88 is slidably 'iournalled in a bushin'gfblock 90.-.sothat:a bifurcated-tip 9| thereof maybemovedinto engagement with-a connecting p-inL-92ionttheinduct'or.unitlfl.(Fig. 2). The buShingwQD is verticallytadjustable. in thechannel 81 (Fig. .6) toprovide for inductor .units 19 of varying heights :and is secured in a predetermined position by aknurled thumbscrew 93 which extends through.-a.slot:t94in the .arm-.:84 to engage a threadedaperturein theb'ushing block 90. A pointer.95is securedto the-bracket '90 .so :as to cooperate with the scale portion 1I on' the cover plate'iiliv A constant frequencyvoltageis applied toany one of. a pluralityof coils 96' 211111591 ('Fig..'9)-'of the inductor-unit"! (Fig. :2) from 'an adjustable frequency oscillator 98 (Fig. 9) by imeansof connection .box 99 (Figs. land 2) and-a plurality of conductors I100. jTheenergizationof'one of the coils-96 or 91 (Fig. 9) produces-anielectromagnetic field which is detected by an electromagnetic pick-up coil IIU (Fig. 3).

Theelectromagnetic.pick-up coil IN) is secured within a slot I I I (Figs. 2 and 3) in a cylinder I I2 which extends upwardly through openingzfifl (Figs. 1 and 3) into the inner cylindricalcavity of the inductor vunit 'lfl (Figs. 2- and 3). Thelcoil III) is connected to'an :electromagnetldfield strength indicator II3' such as a voltmeter (Figs. land 9) by a pair of conductors H4 which. extend from the coil I 59 through an aperture I I5 in the cylinder H2 and a slot II6 (Fig. 2) in the lower surface of the wooden base 2 I to the indicating device H3. A depression IOI (Fig. 3) is provided in the upper extremity of cylinder I I2 tosupport a magnetic compass (not shown).

The cylinder II 2 is mounted for'vertical movement within a sleeve I I1 (Figs. 2-and 3), the upper end of which. is rotatably mounted within a bushing I IS-secured within the aligned openings in the gear housing 59 andplate 55. The lower end of the sleeve H1 is rotatably mounted'within the bushing I8 and is also secured to an indicator arm I I9 which rests upon the upper surface of. plate 25. Cylinder l 12 is secured against rotative'movement within sleeve M1 by a :pin I20 (Fig. 5) which extends through the cylinder H2 andengages a pair of slotsIZIand-IZZ inthesleevelfl.

A journal block I23 (Fig. 2) and a split bearing block I24, which are secured to the indicator arm I I9, rotatahly support a horizontal shaft I25. A pinion I26 (Figs. 3 and5) secured to one end of the shaft I extends through anopening I21 1n the sleeve II1 (Fig. 3) to engage a rack I28 secured to the cylinder II'2. A knob 'I29'(Figs. 2 and 7) secured to the other end of the shaft I25 cooperates with a calibrated dial I and serves to rotate the shaft I25 and the pinion I26 carried thereon to raise or lower the cylinder II2 within the sleeve I I1. The pin I29 cooperating with the slots I2I and I22 (Fig. 2) limits the amount' fby which cylinder II2 can be raised orlowered; vA thumbscrew I40 which extends through both halves of the split sbearingiblockl24 is 'rotatedto lock the shaft 1 I25. andrconsequently the.:cy1inder I I2 ina predetermined adjusted1vertical: position.,

--;Q0nse.quently, 1 rotation .of i the shaft I25 araises.

and -lowers the cylinder :I-IZ iSO l-that :the pick-up coil III) may be positioned "atgtheefiectivehorizontal plane .of the electromagnetic; field. produced byaeither one of the coils-i96orz91 (Fig. 9) within theiinductor 10. The ..rotation-of the :indicator arm III 9 rotates the sleeve H1 and consequently the: cylinder ;I:I 2 so. that the: pick-up coil I I0. carried thereby'may be rotated to'the point of-minimum= electromagnetic field 1 strength within the inner :cavity of inductor 10.

AIheindicator arm I I9 ,(Fig. 1):.iscalibrated in minutes onangular deflectionaeat ascale portion I14I ;-thereof. The scale portion-Iz4I on arm H9 is calibrated from. amid-index mark 1 M2 toithirty minutes 1 (.30) deflection .both .toathe left and the right .of-theindex mark. I42:but "maybe calibrated many other manner. Since the: scale portion I4I issadiacent the scaleaportion 5420f the adjustable plate {29; the two scales-cooperate toprovidea Vernier for indicating the positionofthe arm l I9 with respect to the-zeroz-degree. index mark -32 in degrees and minutes .ofangular deflection. The scale' MI also cooperates with the scale -43 on plate S'I-toprovide a Vernier: for indicating the position of: the-arm I IS) with respect tothe -indexmark 50 in terms. of =.degrees and minutes of angular deflection. A-hole I43 (Figs. land 2) in the indicating arm I I9 isprovided-with an index mark I 44 .to cooperate with either of the-indexs marks 21-and28so-that index marks :21 and -28 can-be aligned I with-the indexv mark 1742 on the arm I I9. Aknurledtknob I 45 zrigidly mounted .on the indicating arm- I-I 9 :acts as a means for'rotatingthe indicating arm.

A bracketdA-G (Fig. 2). which is secured torthe indicating arm I I 9 supports a horizontally reciprocable scribe-I41 having'a hardenedsteel point. Thescribelfl is usedto prick punchtthe outer surface o-ftheinductorll) to indicatevarious ,desired-positions, such as the location of the-magnetic axes of-the icoils ;96.and :91. Thesep-rick punch marks iareused to locate vertical lines whichware :later; marked on the 'outer surface of the inductor ,10. Since the-scribe 4M1 may -;be moved from left to right as viewed in Fig. 2, it is possible 'to mark inductors 10 of various diameters.

Referring now 'to Figu 9 of thedrawings, the adjustable frequency output voltage-from the oscilia-tor 98 is applied to=thecoi1s-96 and 91 of the inductor =10 through a multipleposition switch I:48.-and conductors too. .By: varying the position of thGSWitChslB, the voltage :from oscillator! is, applied to a particular .one or-more of the. coils 96 or 91* toproduce: an electromagnetic field. For purposes of illustration. sthe minimum 1 electromagnetic field strength axes of the coils-=96.-and 91 are designated X-X' and Y--Y,.respectively. The oscillator 98may be replacedby-a battery I49 so that:the coils -:9.6=and 91:.may-be checked for proper I polarity of connection.

All vof the component .partsof the indicating apparatus are 'made'from materials which exhibit. non-magnetic characteristics .so' that -.the apparatus will not impair the accuracy of .-the results i obtained.

t-With the foregoing detailed description in mindgit is believed that the operation. .the testingapparatus will) now be understood.

'F0r- 'p1 1rp0s6s of illustration; it -is' assumed that the: inductor 10 to ;,be= tested is-designed tfor vthe following performance characteristics the. X-X' magnetic taxis of .coil' 96 (Fig '9) -.should1.lie:15 in; a -.clockwise;-tdirection from .-a. predetermined inductor connecting pin 92; the XX' magnetic axis should also be displaced 90 from the YY magnetic axis of coil 91.

In order to prepare the testing apparatus for operation, an attendant inserts a key into the hole 59 in the ring gear 58 and moves the ring gear 58 in a counterclockwise direction to rotate the planetary gears 60 so that the clutch pins 62 are moved outwardly away from the opening 68. The counterclockwise rotation of gear 58 also winds up spring 65 so that after the attendant places the inductor 10 in aligned testing position on plate 66 and removes the key from hole 59, the spring 65 moves the ring gear 58 in a clockwise direction to move clutch pins 62 into engagement with the outer surface of inductor 19 and to firmly grip this inductor in the central position (Figs. 2 and 3). The inductor 16 is placed on the plate 66 so that the desired locating pin 92 is aligned with the zero degree index mark on the scale 1| (Fig. l).

The operator or attendant then moves the bifurcated tip 9| of the locating arm 88 into engagement with the particular connecting pin 92 which is to serve as the locating element for the X-X magnetic axis. The bracket 86 and inductor 18 are rotated in a counterclockwise direction until the pointer 95 which cooperates with the scale 1I indicates that the pin 92 engaged by the tip 9I is displaced 15 clockwise from the zero degree index on the scale H. In this position the XX axis of coil 96 theoretically should be aligned with the index mark 36 since the zero degree index mark on scale H and the index mark 36 are in alignment. Thumbscrew 83 is then tightened to clamp bracket 80 in this position.

The operator now connects the plurality of conductors I66 to the plurality of connecting pins 92 so that each pair of conductors I connected to each of the coils 96 and 91 forms a completed circuit to the oscillator 98 through switch I48. Next, the attendant moves the arms 25 and H9 relative to each other until the index marks 26, 32, 33, 36 and I44 are in perfect alignment.

Then, the operator manually moves switch I48 to apply alternating cm'rent voltage of the desired frequency to the coil 96. Knob I29 is then rotated to a predetermined position so that the electromagnetic pick-up coil I I0 is at the proper elevation within the cylindrical cavity of the inductor 16 under test. The proper elevation of the coil III] is determined by a visual inspection of scale I30. The coil III! is secured in this adjusted position by turning thumbscrew I46 to clamp the shaft I25 within the split bearing block I24.

When the coil H0 is properly positioned within inductor 1!], the indicating arm H9 is manually rotated until the voltmeter II3 shows a minimum field strength reading. At this time, the operator observes the adjacent scales 42 and MI to determine the displacement of the magnetic axis X-X from the zero index mark 36 in terms of degrees and minutes. If the displacement of the XX' axis from index mark 36, and consequently from the locating pin 92, is greater than the allowable tolerance range, the inductor 16 is rejected. If the inductor is acceptable, the scribe I41 i then moved to mark a reference point representing the X-X' axis on the outer surface of the inductor unit 10.

The displacement of the XX' axis being acceptable, the operator loosens thumbscrews 3| and moves the scale plate 29 until the index mark 32 is in alignment with the indicating arm index mark I42. The scale plate 29 is secured in this position by tightening thumbscrews 3I. Thi provides a permanent record of the displacement of the X--X' axis which the operator can refer to at the completion of the test.

Thumbscrew 26 is then loosened to allow quadrant plate 25 to be moved to realign index mark 28 with mark I44 and consequently with index mark 32. Thumbscrew 26 is tightened to secure quadrant plate 25 in this position. Thumbscrews 39 are then loosened and scale plate 31 is moved to realign index marks 50 and 21. Since marks 21 and 28 are displaced from each other by ninety degrees the realignment of marks 56 and 21 moves scale plate 31 into a position to indicate the displacement of the indicating arm II9 with respect to a point ninety degrees (90) removed from the actual position of the X-X' axis of coil 96.

Switch I48 is then moved by the operator to apply voltage to coil 91 and to remove the en ergization from the coil 96. Next, the operator rotates indicating arm I I9 until a minimum field strength indication is observed on the voltmeter II3 which indicates the YY axis of coil 91. By observing the relative positions of scales 43 and I, the operator determines whether or not the displacement of the Y--Y axis of coil 91 from the XX' axis of coil 96 is within the acceptable tolerance range. The operator marks the position of the YY axis on the outer surface of the inductor 10 by moving the scribe I41 to produce a punch prick reference hole. If the position of the YY axis with respect to the X-X' axis is acceptable, the operator prepares the inductor 19 for a polarity test.

To prepare the testing apparatus for the polarity test, the operator opens switch I48 to remove the alternating current voltage from the coils 96 and 91 and replaces the oscillator 98 with the battery I49. A magnetic compass is then placed in the depression IGI (Figs. 3 and 10) and the movable base plate 23 is rotated until the needle of the compass forms a forty-five degree (45) angle with each of the mutually perpendicular X-X and Y-Y index marks on the top of the cylinder III in Fig. 10. By positioning the needle of the compass midway between the X-X and Y- Y' index marks, the influence of the earths magnetic field is minimized and the needle is equally free to rotate toward either of these marks as an indication of the vectorial direction of the electromagnetic field produced by either of the coils 86 and 91. The battery I49 is then sequentially connected to each of the coils 96 and 91 and the direction and degree of deflection of the compass needle produced by the energization of each coil 96, 91 is observed by the operator as an indication of the direction of current fiow through these coils and, consequently, of the vectorial direction of the electromagnetic field produced thereby. The battery I49 is then replaced by the oscillator 98 and alternating current voltage is applied to each of the coils 96 and 91 to remove any residual magnetism produced by the direct current voltage of battery I49.

The operator completes the test of the inductor 10 by manually removing the conductors I09 from the pins 92, moving the locating arm 88 out of engagement with the locating pin 92, and rotating the ring gear 58 in a counterclockwise What is claimed -l.*Anapparatus fo determin gand indiratinr'z-- the relative positio magnetic a s prpdti'ced} by -a multiple coil ndu'ctdr, -w-h pparati-1's{ comprises means rcrsequenuany "energizing-3 each of the coils of the inductor to produce a series 'of difierent electromagneti ds means for indicating the-angular pos n tromagnetic field strengtli ofeachcoil; and means for measuring the angular, separationbetween the successive minimum field stiength creations.

2. An apparatusTor -determining and indicating theposition of the magnetic axis of an elec-w tromaenetic fi ld of. an inductor-unit With-IQSPQQI to a connecting pin of the inductor unitgicomje prising. a scale, meansfor securing? the connect ing pin: ina predetermined positionzwithzrelation to the scale, means formenerg-izingthe inductor unit to:produce. an electromagneticfield having: a magnetic axis,.-a; rotatable piclg-up coil mounted in the electromagnetic field, a, Scribe cooperating with' said"scalet6"marl' the surf the inductor unit at said magnetic axis.

3. An apparatus for determining the position of the magnetic axis of an electromagnetic field produced by an inductor with respect to a connecting pin of the inductor, comprising inductor supporting means, connecting pin locating means for securing the inductor in a predetermined position on the supporting means, means for energizing the inductor to produce an electromagnetic field, a rotatable pick-up coil positioned within said field, means for moving said coil to the position of minimum electromagnetic field strength, and a scribe for marking on the surface of the inductor to indicate the angular displacement between the position of the connecting pin and the position of the pick-up coil at the point of minimum field strength.

4. An apparatus for determining and indicating the angular separation between magnetic axes of a multiple coil inductor comprising a base, inductor holding means secured to the base, electromagnetic detecting means rotatably mounted on the base and extending into electromagnetic fields produced by the inductor, and calibrated means secured to the detecting means for indicating the amount of movement of the detecting means to provide an indication of the positions of the magnetic axes of the electromagnetic, fields produced by the inductor.

5. An apparatus for indicating the angular separation between magnetic axes of a multiple coil inductor comprising a base, inductor holding means secured to and spaced above the base, electromagnetic detecting means rotatably mounted on the base and extending into electromagnetic .fields produced by the inductor, a first calibrated means secured to the base, and a second calibrated means secured to the detectin means and movable adjacent the first calibrated means so as to indicate the movement of the detecting means relative to the base.

6. An apparatus for indicating the angular separation between magnetic axes of a multiple coi1 inductor comprising a base, inductor holding means secured to and spaced above the base,

minimum elec- SU has.

a" second calibratednieans secured tothedetecting mean's f and ems-vane adjacent the first calibrated meme to produce an indication of the relative movement between" the detecting lilea'n's' and the base.

7'; ="An"apparatiisfor indicating the relative po sitlons of a --p1ura1ityor magnetic axes produced byamuuipie jco'il inductor, which apparatus com '15 prises aba'sei anfinductorholding means secured to thfe base an adjustable", indu tor p si n means" mounted on the holding means, elect'ro magneticdetectingni a'hSrotatably mounted on' mebaseane-extendmg into electromagnetic fields produced by-the inductor, a-firstcalibrated me'ans' secured--to'*the*base',' and"- a "second calibrated means-"securedto the detecting means and in ableadja enttheifirst calibratedi means to proovementiof the detecting" diice summation-cf f m'eans relativeto the-base; v Y 8 Anapparatus'for indicating therelative p tions o magnetic axsfprodiiced 'by a multip coil "nd or, which apparatus comprises a ares; ent inductor-holding m'ean isecured' I ald u'stable 'inductorjfpositionin mounted od the quentially energizing each of the coils in the inductor to produce a series of electromagnetic fields, electromagnetic detecting means extending as into the electromagnetic fields and rotatably mounted on the base, means for varying the vertical position of the detecting means with respect to the fields, a plurality of scales secured to the base, and a calibrated means secured to the de- 4h tecting means and movable adjacent the plurality of scales for indicating the movement of the detecting means relative to the electromagnetic fields.

9. An apparatus for determining and indicatin the relative positions of a plurality of magnetic axes of a plurality of electromagnetic fields produced by a multiple coil inductor, which apparatus comprises a base, an apertured inductor supporting plate secured to and spaced above the base, a sleeve rotatably mounted in the base, a

cylinder slidably mounted in the sleeve and extending upwardly through the aperture in the plate, an electromagnetic detecting means secured to the cylinder, means for raising and lowering the cylinder within the sleeve toyvary the vertical position of the detecting means, a calibrated indicating arm secured to the sleeve,

and a scale secured to the base and cooperating with the calibrated arm to provide an indication of the amount of angular movement of'the arm and extending upwardly through the aperture in the plate, electromagnetic detecting means secured to the cylinder, means forlraisingand lowering the cylinder within the sleeve to vary the vertical positions of the detecting means, means for locking the cylinder in a desired verti- 7 cal position, a calibrated indicating arm secured I 6 1131 holding means; means for 11 tothe sleeve and resting on the base, a plurality of, scales movably mounted on the base, and means for locking the scales in a desired position on the base to cooperate with the calibrated arm for indicating the angular movement of the arm and detecting means.

11. An apparatus for determining and indicating the position of a connecting pin and a magnetic axis of an inductor unit comprising means for energizing the inductor unit to produce an electromagnetic field, detecting means rotatably mounted within the field to determine the magnetic axis of said field, means cooperating with said detecting means to indicate the angular displacement of the inductor connecting pin with respect to said magnetic axis, and means cooperating with said detecting means to mark the surface of the inductor unit at said magnetic axis.

12. An apparatus for determining and indicating the relative positions Of a plurality of magnetic axes produced by a multiple coil inductor, which apparatus comprises a base, an apertured inductor supporting plate secured to and spaced above the base, an inductor holding means cooperating with the inductor supporting plate, a sleeve rotatably mounted in the base, a cylinder slidably mounted within the sleeve and rotatable therewith and extending upwardly through said aperture in the plate, electromagnetic detecting means secured to the cylindenmeans for moving the cylinder to adjust the vertical position of the detecting means, a scale attached to said adjusting means to indicate the vertical position of the detecting means, means for locking the cylinder and the detecting means in a desired vertical position, a calibrated indicating arm secured to the sleeve and resting on the base, a plurality of scales movably mounted on the base, means for locking the scales in a desired position on the base to cooperate with the calibrated arm for indicating the angular movement of the arm and detecting means, and a scribe mounted on said indicating arm and rotatable therewith for marking the positions of the magnetic axes as determined.

HARRY DUKE. WALTER BAKER GREENWOOD. JEAN THOMAS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,344,388 Eisenmann June 22, 1920 1,526,391 Stewart Feb. 17, 1925 2,167,490 Ryan July 25, 1939 2,490,102 Stein Dec. 6, 1949 2,500,680 Herrick et al. Mar. 14, 1950 2,531,807 Pangher Nov. 28, 1950 OTHER REFERENCES Instruments, May 1949, volume 22, pages 432, 

